The corner whitening filters were not switching, with an error message invalid data chn and readback different for Refl 9 and refl air 9, and for POP we had an error message invalid data for channels 1, 2, 3 and 4.
Daneil fixed this by going to the system manager for the corner, finding the X gateway under device 1, corner MSR L0, Corner MSR L8_9 Vertex, going to the Online tab, and clicking on several of the buttons under state machine (Init, pre-op, safe op, op) in an order that seemed random to me.
I am just writing down the solution to this problem so that we can look it up next time it happens.
This happened again, we repeated what we did, on the Corner Chassis 2 L-2 (X-gateway) under Online the current state was safeop. We hit a bunch of buttons (including clear error) until it arrived in OP. We repeated this for L-1, which was also in safe OP.
An alternative solution would be to restart h1ecatc1